Control unit



Jan. 8, 1935.

Filed June 26, 1931 J. E. GRIMM CONTROL UNIT 2 Sheets-Sheet l Jan. 8,1935-. J. E, GRlMM 1,986,892

CONTROL UNIT Filed June 26, 1931 2 Sheets-Sheet 2 lnon m Patented Jan.8, 1935 PATENT oF ICE CDNTR John Edward Grimm, Dayton,

mesne assignments, America, New York, Delaware Application June 26,

1 Claim.

This invention relates to a radio receiver and in more particular to aremote control thereof. In the present-day receivers that are usuallymounted in cabinets, the controls are mounted 5 on the outside of thecabinet. With such an arrangement it is necessary for the operator ofthe receiver to be in the immediate vicinity of the receiver every timethat it is desired to tune in on another station or to change the volumeoutputof the receiver. 'I'his is objectional in that it is oftennecessary for the operator to either remain near the receiver or to goto the receiver at frequent intervals to manipulate the controls forsatisfactory reproduction.

An object of this invention is to provide a remote control for the radioreceiver that is efiicient, dependable, easily constructed, thatrequires few parts and that improves upon the performance of the modernradio receiver. This has been accomplished by providing an oscillatorand a detector supported in a suitable casing and attached to the radioreceiver by a cable.

Another object of this invention is to provide a support for the remotecontrol. This has been accomplished by combining the remote controlapparatus with a suitable stand such as a tobacco stand.

Another object of this invention is to provide a stand that is soconstructed and arranged that if it is upset it will upright itself,thereby protecting the apparatus, such as the tubes, mounted in theremote control unit. This has been accomplished by providing a pedestalfor the stand that has a loaded semi-spherical base having the center ofgravity below the center of curvature. Such an apparatus upon beingupset will upright itself.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of one form of the presentinvention is clearly shown.

In the drawings:

Figure 1 represents a conventional radio receiver provided with a remotecontrol;

Figure 2 discloses a plan view of the remote control unit;

Figure 3 shows a modification of the stand for the remote control unit;

Figure 4` discloses a schematic wiring diagram of a portion of thecircuit of the radio receiver and the circuit of the remote control.

Figure 5 discloses an end view of the cable extending from the radioreceiver to the remote control unit;

Figure 6 discloses a side elevation of the cable with parts broken awayso as to better illustrate the construction thereof.

The remote control unit may be used with practically any modern radioreceiver such as a tuned OL UNIT Ohio, assigner, by to Radio Corporationof N. Y., a corporation of 1931, Serial No. 546,993 (Cl. Z50-14) radiofrequency receiver, a superheterodyne receiver, a super-regenerativereceiver or the like. When the remote control Luiit is used inconnection with a receiver7 the tuning device on the receiver is set insome predetermined position, as for example to a wave length just alittle longer than the longest wave length found in the usual broadcastrange.

The remote control unit contains a tuning device or station selector, anoscillator, and a detector. Either a separate or a single tubeoscillator and detector may be used so that beat frequency is producedby combining the desired incoming signal with locally generatedoscillations to produce a beat frequency equal to the frequency forwhich the receiver is set. The incoming signals may be signals withinthe usual broadcast range or signals outside of the usual broadcastrange usually referred to as short wave signals. The remote control unitcould, of course,

be provided with removable coils so as to change its range from thebroadcast range to the short wave range and vice versa.

In the preferred embodiment as best seen `by the vschematic wiringdiagram of Figure 4, the receiving system includes the remote controlunit, the intermediate amplifier, the cable connecting the remotecontrol unit to the intermediate amplifier and an audio amplifier.Intermediate, as here used, designates the stages of amplification inthe receiver that amplies all signals above audio frequency whether itis a tuned radio frequency, a superheterodyne receiver or otherreceivers.

In the remote control unit is found the detector 50 and the oscillatortube 52. The oscillator as is well known to those skilled in this artincludes the anode circuit which has an inductance 54 coupled to aninductance 56 found in the grid circuit. The frequency of the locallygenerated oscillations may be adjusted by changing the resonant circuitincluding the inductance 56 and the condenser 66.

A uni-control has been provided for actuating the condenser 58 in thetuned frequency stage which includes the secondary 60 of the transformer62 having the primary 64 in the input circuit and for actuating thecondenser 66 which is arranged to control at a, certain predeterminedfrequency and at substantially constant frequency difference theoscillator circuit comprising the capacities 68, 70 and 72 and theinductance 56. The inductance 56 is coupled to an inductance '74 havingone terminal grounded at 76 and the other terminal connected through acondenser '78 to the cathode 80 of the detector 50.

A suitable B-voltage is supplied to the plate 84 from the B-source inthe radio receiver through a conductor 82 through a voltage divider 86having one terminal grounded at 88 and through a resistance 90. TheB-voltage is supplied to the plate 92 of the detector 50 from the samesource through the conductor 82, the choke 94 and the coil 96.

A direct current grid bias is supplied to the grid 98 through a highreactance coil 100 and a resistance 102 that are connected in seriesbetween the cathode and ground 104. The inductance 100 oifers a veryhigh impedance for the oscillator voltage, and a high resistance for adirect component of the plate current. The resistance 102 may be omittedby increasing the impedance of the reactance coil 100. f

The output of the detector is connected to the input 109 of theradioreceiver through a condenser 106 having one terminal connectedintermediate the coils 94 and 96 and the other terminal connected to asuitable grounded resistance 108 that is provided with a suitable tap110 connected to a lead 112, a blocking condenser 114 and a loading coil116.

The inductance 116 has been introduced into the line so as to counteractthe capacity effect existing between the several leads. The size of theinductance 116 is dependent upon the length of the cable and itsdimensions and upon the frequency at which the particular receiver isset. The intermediate stage or stages are set to a frequency preferablyat one end of the range where it remains regardless of the stationselected by the remote control unit. After the signal is amplifiedthrough the intermediate stages it is then detected and again amplifiedthrough the audio frequency stage, which in this particular modificationincludes the push pull tubes 120 and 122.

The current in the push-pull amplifier is used to energize the filamentor cathode 80 and the filament or cathode 124 of the detector and of theoscillating tube respectively, in the remote control unit. If this platecircuit does not furnish the requisite current for the filament in thetubes in the remote control, these filaments may be energized from anysuitable source of current, as for example from a voltage divider, incase an alternate current is used to energize the receiver. A choke 126has been inserted in the lead connecting the plates of the push-pullamplifier to the filaments in the remote control unit so as to isolatethe high frequency signal current, the local generator oscillations andthe beat frequency from the audio circuit. Grid bias for the push-pullamplifiers 120 and 122 is supplied through the voltage drop across theresistance 128.

f The cable connecting the remote control unit to the radio receiverincludes the leads 82, 112 and 140, enclosed'within an armoured shield142, grounded at 143. The leads 146 and 148for the antenna is carriedoutside of the armour so as to eliminate any heterodyning effect betweenthe incoming signal and the signal transmitted from the remote Vcontrolto the intermediate stage. The armoured cable and the antenna lead-ins146 and 148 may be covered by a suitable covering 149 so as to hold theparts together and so as to improve the appearance of the cable. 'Iheabove circuits per se do not form the subject matter of the presentapplication, but are used to illustrate the present invention.

In the modification disclosed in Figures 1 and 2 the radio receiver ishoused within the cabiof curvature 158.

net 150 and they remote control unit is housed within the case 152carried on a suitable pedestal 154, provided with a curved base 156 thathas the center of gravity CG located below the center The cable 145connects the radio receiver circuit to the remote control circuithousedwithin the casing 152. The casing 152 which is preferably made from asuitable metal is provided with a pair of knobs 160 and 16,2,y theformer controlling the condenser 58 and the condenser 66, and the latteradjusting the tap 110 on the potentiometer 108 so as to change thevolume output. A shaft 164 which connects the knob 160 to the condensers58 and 66 carries a dial 166 that cooperates with the indicants 168integral with escutcheon plate 170 carried by the cover 172 of thecasing 152. The cover 172 is also provided with an ash tray 174 so thatthis stand for the remote control also serves the function of a tobaccostand so as to reduce the number of pieces of furniture.

In the modification disclosed in Figure 3 a casing 182 provided with acover 184 carrying an ash tray 186 and having the control knobs 188 and190 encloses the remote control unit. The arrangement of the dial andescutcheon plate is the same as in the modification in Figures 1 and 2.

The casing 182 is supported upon a -pedestal 192 provided with asuitable base structure 194. In the modication disclosed in Figure 3,the base is much broader as it is not provided with a curved base thatautomatically uprights.

While the form of embodiment of the present invention as hereindisclosed, constitutes a preferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimwhich'follows.

What isclairned is as follows: y d

In combination with a radio receiving system having its input adjustedso as to be resonant to a frequency at one end of the broadcast range, apower supply circuit for energizing the system and means adapted forconnecting the input of the receiving system to a broadcast signalcollector, a control device for said radio receiver, comprising a casenormally disposed at a point remote from the receiver, a frequencychanger circuit disposed within said case for converting selectedsignals of said broadcast range to the frequency to which the receivingsystem resonant input circuit is tuned, a broadcast signal selector insaid case connected with the frequency changer circuit, means connectingthe said receiver collector connection means to said selector,additional means connecting the output of the frequency changer circuitto said receiver input, said additional means including a variabledevice disposed within said case and adapted to be operated at saidremote point for controlling the amount of energy transferred from thefrequency changer circuit to the receiver input, means for connectingsaid power supplycircuit to the frequency changer circuit to energizethe latter and a cable housing all of said connecting means said cablebeing provided with a shielding tubing arranged so as to shield themeans for connecting the receiver controller connection means to theselector from the other connecting means of said cable.

JOHN EDWARD GRIMM.

